The device now used for the introduction of scrapers into piping systems, known as a thrower, has its principle of operation based on switching the flow of the pipe-line fluid to a chamber, where the scraper (which may be a pig, a foam-pig, an inflatable sphere or a foam-sphere has been introduced previously. The fluid flow passing through the chamber displaces the scraper from the chamber to the piping system. The devices now used present some operational problems:
The need of using three valves to attain this interconnection; PA1 The impossibility of introducing a foam-pig or sphere into the existing piping system through a connection; PA1 Difficulties of automation for throwing spheres, due to the large number of valves and mechanical devices involved; PA1 Throwing of the foam-pigs or spheres manually; PA1 Risks of operational procedures; PA1 The great danger of accidents in constantly opening the throw chamber. PA1 Lower installation cost. Only a valve is necessary for interconnection with the piping system; PA1 Less space needed for installation; PA1 Introduction of the foam-pig or sphere into the existing piping system through the connection (valves) becomes possible; PA1 Automation for throwing foam -spheres and foam-pigs becomes possible. PA1 A less aggressive environment and less danger of accidents, because the opening of the chamber of the NC-SR thrower occurs frequently; PA1 Lower operational and maintenance cost, since wear due to operation of the valves is less frequent, as well as the number of valves; PA1 Less danger of operational mistakes in throwing operations; PA1 No need for special chamber covers, because of the lower frequency of chamber openings of the NC-SR thrower.